News / Features / January 3, 2024

Margenot’s Soils Lab Providing Valuable Piece to Understand Agroecosystems 

As an associate professor of soil science, Andrew Margenot specializes in soil biogeochemistry to understand agroecosystem functions such as nutrient storage and cycling, crop production, contaminant filter and storage, and climate regulation.

Margenot profiling soils in coffee agroecosystems in Guatemala. This work, conducted via participatory research with smallholder farmers, seeks to identify means to increase coffee yield and quality to improve smallholder income in a region that is largely economically dependent on this tropical crop.

To find the dirt on Andrew Margenot, you may need to sift through the literal dirt. Currently an associate professor of soil science, Margenot specializes in soil biogeochemistry to understand agroecosystem functions such as nutrient storage and cycling, crop production, contaminant filter and storage, and climate regulation. 

His research team of 40 personnel has approximately 35 active grants, with 80 percent of those projects focused on the Midwest context. The emphasis of this work is on nutrient management, soil organic matter cycling and soil health, involving direct work with stakeholders ranging from USDA NRCS to farmers via a lot of on-farm research.

“We are interested in understanding outcomes of practices: why is a practice working or not for a given outcome of interest?” Margenot explained. “Can we explain those outcomes in order to predict future outcomes? We work with the Agrosystem Sustainability Center (ASC) to assess and explain those outcomes and study the biogeochemical mechanisms that underpin agroecosystem functions.” 

Although the University of Illinois sits in the heart of some of the richest soils in the world, Margenot cut his teeth on high weathered, low fertility soils in the tropics, notably East Africa and Latin America. 

“The soils in these parts of the tropics have low fertility because they are old,” Margenot explained.”It’s like a 95-year-old person.”

Having studied on the coasts, with a bachelor of arts degree  from Connecticut College, majoring in both philosophy and biochemistry and molecular biology, and a PhD in soil biogeochemistry from UC Davis, he thinks there are several misconceptions there about the Midwest.

“ I think that we as a field of research have mistaken ecological simplicity of the Midwestern agricultural landscape with biogeochemical simplicity. It’s not simple, and the problems we face are not easily solvable,” he said.

A current topic of focus is nutrient management, focused both on improving fertilizer use efficiency and how nutrient losses practices can maximize efficiency and minimize losses, and why.

Margenot stands in a soil pit next to Jim Isermann at Isermann Farms in LaSalle Co., IL. The pit profiles the official state of Illinois soil, the Drummer series. Essential to the approach taken by Margenot’s team is start with farmers, be they in the Midwest or in Guatemala or Kenya, to understand the challenges that agroecosystem managers face and how researchers can better align scientific approaches to target real-world solutions.

“As part of that, we build a lot of tools to understand the system and test mechanisms,” he added. “If you don’t have a tool, you have to build it to understand why something is changing.”

Such as finding the right level of phosphorus in the soil to support high crop yields while reducing run-off losses. Margenot calls phosphorus the “Goldilocks nutrient” because it is hard to get it “just right”. Margenot’s team has also discovered that in assessing the nutrient losses to the surface water, researchers have not been accounting for natural losses through eroding streams. 

“A portion of our phosphorus losses are due to practices from 60-80 years ago,” Margenot said. “We call these legacy phosphorus. We have a really poor understanding of legacy nutrient losses, but the problem is that is what is driving our losses today. So it’s an inexact science.”

Although headquartered in central Illinois at the state’s flagship land grant campus, Margenot diversifies his research across fields in northern, central and southern Illinois, the greater Midwest, and in the tropics. 

“In order to make our findings and discoveries applicable globally, we try to understand the why of things,” he said. “Even in Illinois, you go from a very cold climate to the beginning of a nearly  subtropical climate. We tend to be spoiled here because even the ‘lesser’ soils in southern Illinois are still very fertile compared to weathered soils in the tropics.  If we can explain how soils function at a biogeochemical, process-based level, then those same insights can be applied to understand soils and agroecosystem functions anywhere, from the red oxisols of Kenya to the black mollisols of Illinois.”  

Margenot also uses this approach to demonstrate that while one agroecosystem management practice may work well in one context, positive trade-offs  are not necessarily universal. For example, cover crops might increase yield in places with marginal soils like southern Illinois or Missouri, but might not in areas where soils are richer.

“Cover cropping is in some ways a Swiss Army knife: you can customize cover crops for all kinds of outcomes,” he added “Are there benefits of using cover crops to reduce soil erosion by wind or nitrate leaching? Absolutely. That’s what we should be thinking about cover cropping in the ‘flat and black’ in the heart of the Corn Belt. In the rolling ground of the Ohio River Valley that bounds the southern extent of the Corn Belt, we know that cover crops increase yield – in contrast to the central Corn Belt – while  also mitigating soil erosion by gravity.”

A severely eroding streambank in southern Illinois. Streambank erosion is an overlooked but critical contribution to non-point phosphorus and sediment loads to surface waters. Margenot’s team is leading an ASC project to quantify – for the first time – streambank erosion and its contributions to P loads in Illinois. These results will directly inform Illinois and US EPA strategy on improving water quality in the Midwest and the Gulf of Mexico.

That is an example of the kind of innovative research that Margenot and others at ASC hope can improve processes and outcomes in both Illinois and around the globe. They are at the forefront of addressing the growing problems of climate resilience and food security. 

On the microscale, he is teaming with ASC to help update the Illinois Agronomy Handbook, where some of the recommendations are more than 80 years out of date. The project is funded by the National Science Foundation (NSF) and the National Research and Education Network (NREN).

“We aren’t great at keeping up with understanding these systems because we are not keeping up on the basics on how we manage them,” he reasoned. “The amount of phosphorus, potassium, and nitrogen recommended for fertilizer are based on efforts from the 1960s.”

Margenot also notes that much of the recommendation is from sampling the top six inches of the soil. Their updates will include results that will account for soil specific reserves of nutrients at the root level some three to four feet deep. Margenot’s team is applying biogeochemistry to understand fertilizer fate, use and non-fertilizer soil contributions to crop uptake. 

“The idea here is to understand how the biology of soils and native reserves in the subsoil can contribute to crop uptake,” Margenot said. “To me, that’s where agroecology becomes good agronomy, and offers a more biologically inclusive approach to nutrient recommendations to improve the farmer’s bottom line. With co-benefits to water quality. That’s something the traditional agronomy approach has missed, and many ecologists have turned their nose up in favor of more pristine, unmanaged ecosystems. I think the agroecosystem is where the action is at, and frankly, the need.” 

On the environmental side, Margenot’s team is part of an ASC Illinois NREC project, which  is gathering data on erosion of streambanks and resulting phosphorus loading across the major and representative HUC-8 watersheds of Illinois. While studies of Baltic Sea basin states like Germany and Poland, have found that one-third of their entire phosphorus loss have come from eroding stream banks, no such data exists in Illinois. The United States Environmental Protection Agency has mandated that by 2025, states and federal agencies report on progress toward achieving programmatic commitments. This study will directly inform the Illinois Nutrient Loss Reduction Strategy, the report from the State of Illinois. 

“If we have a similar result as our colleagues in the Baltics, we will need to reallocate resources in order to solve the problem,” Margenot said.  

As ASC strives to be a global leader in monitoring and modeling agroecosystems for improving sustainability under climate change, Margenot’s team will be valuable in bringing research to understand the role soil plays.

Magenot concluded, “Applying basic biogeochemistry with a systems approach can provide insights to help close gaps that have only grown over the last 50 years.”

About the Agroecosystem Sustainability Center (ASC): The Agroecosystem Sustainability Center was founded in 2021 to lead global efforts in harmonizing sustainable food production with thriving ecosystems. The Center strives to revolutionize agricultural systems through research, collaboration, and engagement, bridging science and practice for agricultural productivity and ecosystem sustainability. Centered in the heart of Midwest on the campus of the University of Illinois Urbana-Champaign under the umbrella of both the College of Agriculture, and Environmental Sciences (ACES) and the Institute of Sustainability, Energy, and the Environment (iSEE), ASC is positioned at the critical intersection of academia, industry, policy, and on-the-ground practice. ASC is creating a diverse and dynamic hub for driving change and is committed to transforming its research into practical and scalable solutions, fortifying our ecosystems, bolstering farm profitability, and empowering agricultural systems to proactively mitigate and adapt to the realities of climate change.

Media Contact: Mike Koon, ASC Communication Lead (mkoon@illinois.edu)